Treating hydrocarbon oil



Dec. 27, 1932. R, E, MANLEY 1,892,283

TRATING HYDROQARBON OIL Filed Dec. 27. 1927 26 NAP/IWA 3.16/7 'IMS/0COLD /V/ PH THA F/LTE'R y PUMP Off/LER VHCw/M PUMP g1/wanton vp @M 5. 7%

Patented Dec. 27, 1932 UNITED STATES PATENT oFFlcE ROBERT E. MANLEY, OFPORT ARTHUR, TEXAS, ASSIGNOR TO THE TEXAS COMPANY, OF NEW YORK, N. Y., ACORPORATION OF DELAWARE TREATING HYDROCARBON OIL Application ledDecember 27, 1927. Serial No. 242,621.

This invention relates. to a process for treating hydrocarbon oil andmore particularly to a process of treating wax-bearing hydrocarbonlubricating oils to effect removal of solid and semi-solid waxyconstituents whereby the temperature of congelation of the oil isreduced.y Considered broadly the invention comprises a process whereinwax-'bearing hydrocarbon lubricating oil.: which may have been subjectedto any desired preliminary relinin treatment, is chilled to atemperature whic will effect precipitation of the solid and semi-solidwaxy constituents of the oil, after which the precipitated constituentsare separated from the oil by filtration at temperatures below theirprecipitation temperature. To aid in the separation of wax constituentsfrom the oil, a comminute solid material or filter-aid is mixed with theoil, the filter-aid and the precipitated wax being deposited togetherupon the filter. The wax and the filter-aid material are then separatedand the filter-aid is dehydrated and used again in dewaxing furtherwax-bearing hydrocarbon oil.

rlhe invention may be^readilyunderstood from a description of theprocedure of the process considered in connection with the accompanyingdrawing which represents a diagrammatic sectional elevation of anapparatus which may be employed for carrying on the various steps of theprocess. The apparatus illustrated in the drawing is shown an describedmerely for the purpose of aiding in understanding the process and it isto loe understood that any other suitable apparatus may be substitutedfor that shown.

Referring to the drawing, there is illustrated a source of oil to bedewaxed such as tank 11 anda source of a suitable diluent,for examplenaptha, such as the tank 12. A mixing vessel 13 is provided wherein thewaxbearin -oil and'diluent may be mixed if so desire From the mixingvessel 13 the waxloearing oil, which ma or may not be diluted, is forcedby means o the pump 14 through the chiller 15. The chiller may be of anysuitable design and ispreferably the tubular type in which the oilpasses through a pipe surrounded by a jacket through which cold brineflows in a direction counter to the flow of oil. After having beenchilled to the proper temperature to eect precipitation of the waxyconstituents, the oil is introduced into the insulated mixing tank 16fitted with a suitablel p mechanical agitating device 17 wherein the oilis thoroughly mixed with the proper quantity of a comminuted solidmaterial or filter-aid, such for example as diatomaceous earth. From thecontainer 18 the filter-aid material may advantageously be supplied tothe mixing tank in the form of asuspension or slurry by mixing witheither naphtha or a portion of oil which has previously been dewaxed.Accordingly, a means for supplying cold naphtha to the tank 18 isprovided in the line 19 leading from a suitable source (not shown). Thetank 18 is fitted with mechanical agitating means 20 provided tomaintain the filter-aid in a substantially uniform suspension in thenaphtha. Although the mixing tank 16 is heavily insulated there wouldnormally be some loss in refrigeration to the atmosphere and accordinglyan additional Chiller 21 is provided and a pump 22 connected theretothrough the lines as shown, whereby the contents of the tank 16 may becirculated through the chiller to maintain the desired low temperaturein the tank 16.

From the mixing tank 16 the mixture of chilled oil and diatomaceousearth is forced by the pump 23 through the filter press 24 which isheavily insulated and which may be also brine-jacketed in order tomaintain the chilled oil at the desired low temperature. The filterpress may be of any suitable type and it has been found from experiencethat the type of pressure filter known as the Kelly filter isparticularly satisfactory for this work. After passing through thefilter the oil is discharged through the connection at 25 into thestorage tank 26 while the precipitated wax and diatomaceous earth aredeposited in a cake upon the filtering surfaces. A container 27 issupplied to receive the cake of wax and diatomaceous earth which may bebil till

with a means tor chilling such as the cooling coil` 29, and a pump 30 isprovided for forcing the cold naphtha through the filter for washing oilfrom the filter cake. A tank 31 with suitable connections is providedfor receiving the naphtha after it has been used in washing the liltercake.

The tank 27 is fitted with an agitating dey vice 32 and a connection 33whereby naphtha may be supplied from a suitable source (not shown). Whenthe filter cake is dumped into the tanlr 27' it is mixed and agitatedwith naphtha to form a suspension which is then pumped by means of thepump 34 through theI connections as shown, to a still 35, fitted withagitating means 36. Heat is applied to the still by any suitable means,as for example the steam coil 37, the temperature being so elevated asto distill od a portion of the naphtha, which carries with it waterabsorbed by the diatomaceous earth during the dewaxing process. From thestill 35 the par. tially dehydrated suspension of the diatomaceous earthin the naphtha solution of wax is pumped by means of the pump 38 into asecond still 39, also yiitted with agitating means 40 and heated bysuitable means such as the steam coil al., wherein distillationcontinues until the diatomaceous earth has been substantiallydehydrated.

From the stills 35 and 39 the distilled products, consisting of naphthaand water, ass off to a suitable condensing system not shown) throughthe connections d2 and 4&3, respectively. After condensation, thenaphtha and water may be separated by a proper system oi traps and thenaphtha returned to the stills it so desired.

From the still 39 the dehydrated suspension is pumped by means or thepump ad through a suitable cooler d5 to the tanlr lli which is ldttedwith agitating means l? to maintain the diatomaceous earth insuspension. The tank i6 serves as a supply tanlr tor a lilter t8 whichmay be oi any suitable design such, tor example, vas that lrnown as theAmerican continuous filter. Herein the diatomaceous earth is depositedupon the filtering surfaces in the form ot a calre while the solutionot" wax in naphtha is withdrawn trom the lter by means ot the Vacuumpump 49 toa tank 50 where it may be stored lor further disposition. rlhelter caire and diatomaceousearthmay be washed by means oi' warm naphthasupplied through the connection at 5l from a suitable source (notshown). A

The lter cake, which consists of diatomavceous earth, moisture-free, andin a form Lacasse the connection 54 from a suitable source (not shown).rllhe diatomaceous earth may then be pumped., in the torna ci asuspension, by means of pump 55 to the tank 18 from which it may beintroduced at the proper time to the mixing tank lt and re-used in thedewaxing of further oil.

The operation of the process in connection with the apparatus shown maybe substann tially as iollows:

'llhe oil to be dewaxed, tor example a treated and ltered cylinder stockhaving a pour test oi' about 70 F., is introduced through the tank 1linto the mixing tank 13 where it is thoroughly mixed with a suitablediluent, 'preferably petroleum naphtha in proportion of about 30 to 60per cent by volume oi the diluent. The dilutedoil is then forced throughthe chiller l5 by means of the pump la and the temperature is thusreduced to the degree desired to edect precipitation of the solid andvsemi-solid waxy constituents contained therein. rlhe temperature towhich the diluted stock is chilled will depend somewhat upon the degreeot dewaxing which it is desired to obtain, which is in turn dependentupon the maximum temperature of congela tion desired in the linished oiland, in general, it may be said that the oil should be chilled to atemperature several degrees lower than the congelation temperaturedesired in nished dewaxed oil. ln the present instance it may be desiredthat the dewaxed cylinder stock have a pour test or congelationtemperature not exceeding approximately 300 F., in which case it will bedesirable to chill the diluted stoclr` to about l5 From the. Chiller l5the diluted stoclr passes inte the mixing tanlr i6 where it is mixedwith a suitable ilter-aid material such as diatomaceous earth, in thedesired propertion, which is in this instance about l0 to 30 pounds otearth tor each barrel oi diluted stock. Illhe diatomacecus earth issupplied trom the tank l8, preferably in the term ci a suspension incold naphtha., llt is of extreme importance that the diatomaceous earthsupplied to the mixing tank i6 shall be substantially anhydrous. llt thedewaxing prccess is carried on at temperatures below 32 l?. any moisturepresent in the earth terms ice which fills up the porous structure etthe earth rendering it so ineticient as to be practically worthless as afilter-aid in the process.. ln general, it will be found that a moisturecontent exceeding 5 per cent by weight will so greatly reduce theeiiciency ot the diatomaceous earth as a filter-aid as to materiallyimpair the practicall o eration et the process when a recovered lter-aidot such high moisture content is used, while tor the best results, themoisture content should not exceed l per cent by weight.

The earth is very nely powdered and the ico lieu

contents of the tank 16 are continuously agitated by suitable mechanicalmeans 17 to prevent settling of the precipitated Wax and the earth. Fromthe tank 16 the chilled diluted oil containing precipitated waxyconstituents and?. diatomaceous earth in suspension is forced throughthe filter 24 by means of the pump 23. The dewaxed oil is dischargedfrom the 4filter through suitable connections at 25 and passes to thestorage tank 26, after which it may be treated in any suitable mannerfor the removal of the diluent to yield the finished dewaxed product Theprecipitated wax and diatomaceous earth are retained upon the filteringsurfaces in the form of a more or less porous cake. When theproper'thickness of cake has been built up on the filter the supply ofoil from the tank 16 is cut of and the filter drained. The cake may thenbe blown with air and washed With cool naphtha from the tank 28 for thepurpose of removing the last traces of oil, after which it may be dumpedinto the tank 27 Where it is mixed with naphtha supplied through theconnection at 33, the material being properly agitated by means of theagitator 32.

During the deWaxing operation described in the previous paragraph acertain amount of moisture is ordinarily absorbed from the oil by thediatomaceous earth. Further moisture condenses from the atmosphere andcollects upon the cold filter cake during the time it is beingdischarged from the filter. As a result, the earth forming a part of themixture in the tank 27, although originally introduced into the systemin a dry state, may be found to have absorbed moisture up to as much as75 per cent by weight or more. vIf such diatomaceous earth were merelyseparated from the wax portion of the filter cake and returned to thetank 18 for further use in dewaxing additional oil, it would be found tobe practically worthless as a iilter-aid material and the process wouldbe substantially inl operative. Accordingly, the earth is recovered by amethod involving dehydration which is as follows:

The contents of tank 27, consisting of a mixture of naphtha, Wax, anddiatomaceous earth, are forced by means of the pump 34 to the still 35.Heat is applied to the still through the steam coil 37, although anyother suitable means for heating the still may be used, and the contentsare maintained in suspension through the action of the agitating device36. Distillation takes place in the still 35 and a portion of thenaphtha and the water absorbed by the diatomaceous earth distills ofr1through the connection 42. The still 35 may be so operated as'to distilloif all of the Water contained in the diatomaceous earth but in theparticular apparatus and example being described, an additional still 39is provided and the contents of still 35 It may be desirable to collectthe distillates from the stills 35 and 39, separating the water from thenaphtha by suitable separating means (not shown) and returning thenaphtha to the stills in order that, through it distillation, more water'may be carried o From the still 39 the dehydrated suspension ofdiatomaceous earth in the naphtha solution of Wax is conveyed, by meansof the pump 44, through the cooler 45 wherein it may be cooled toprevent substantial evaporation of the naphtha, after which it passesinto the tank 46. Here the mixture is maintained in suspension by theagitating device 47 and is fed into the filter 48 where the dehydrateddiatomaceous earth is deposited as a cake upon the filtering surfacesand may be washed free from wax by Warm naphtha supplied through theconnection at 51. The Wax solution passing through the filter is collected in the tank 50, the naphtha contained therein being recoverablethrough distillation.

The filter cake,consisting of dewaxed and dehydrated diatomaceous earth,is discharged to the tank 52 where it may be mixed with naphtha,preferably cold naphtha, wherein it is maintained in suspension throughthe action of the agitating means 53. The diatomaceous earth in thiscondition is suitable for further use in dewaxing oil and, as

desired, may be pumped by the pump 55 back to the tank 18 from which itmay be introduced at proper intervals to the mixing tank 16 and thereemployed in dewaxing further hydrocarbon oil.

The specific example of the invention described in the precedingparagraphs has included a method of effecting dehydration of therecovered filter-aid material which consists in subjecting the materialto distillation in the presence of a volatile fraction of petroleum,such as naphtha. However, other volatile solvents of Wax may be used toreplace the petroleum naphtha, for example, coal tar products and theirderivatives, and also alcohols. It will be understood that the inventionis not limited to a procedure involving dehydration by distillation withvolatile solvents and that other suitable means for the removal of Waterfrom the filter-aid material may be used. For example, after theseparation of wax from the filter cake `obtained from the filter 24, theWax-free diatomaceous earth may be heated to temperatures sufcient todrive off the moisture. An equivalent procedure which may, under 4-Lacasse certain circumstances, prove desirable, is to blow heated gasesthrough the waxfree hlter-aid material. v

Obviously many modifications and variations of the invention, asvhereinbeore set forth, may be made without departing from `the spiritand scope thereof, and therefore, only such limitations should beimposed as are indicated in the appended claims. I claim:

1. The process of dewaXing lubricating oil which comprises subjectingthe oil to a separating treatment, while chilled and maintained at a lowtemperature whereby precipitation of wax constituents is effected andWhile intimately mixed with an inert comminuted solid filter-aidmaterial containing not more than 5% by weightof freev water" comprisinga filter-aid recovered from a previous operation of dewaxing lubricatingoil, whereby said precipitated wax constituents and ilter-aid materialare separated from the oil, and finally separating the iilter- .aidmaterial from the wax whereby the filteraid may be re-used in a similarcycle of opl erations.

2. The process of dewaxing lubricating oil which comprises subjectingthe oil to a separating treatment, while chilled and maintained at a lowtemperature whereby precipitation of wax constituents is effected andwhile intimately mixed with an inert comminuted solid filter-aid materalcontaining nr not more than 1% by-weight of free water "d comprising alteraid recovered from .a previous operation of dewaxing lubricatingoil, whereby "said precipitated wax constituents and filter-aid materialare separated from the oil, and finally separating the filteraidmaterial from the wax whereby the filteraid may be re-used in a similarcycle of operations.

In witness whereof I have hereunto set my hand this 28th da of November,1927.

- RgBERT E. MANLEY.

